Subchannel photonic routing, switching and protection with simplified upgrades of WDM optical networks
First Claim
1. An optical subchannel muxponder that can transmit optical signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the optical subchannel muxponder comprising:
- (a) a subchannel mapper that can map each of a plurality of client signals to a corresponding subchannel within or across a plurality of ITU channels, wherein each ITU channel in the plurality of ITU channels has a predefined ITU frequency and a corresponding plurality of subchannels, and wherein each subchannel has an associated frequency with a predetermined offset from the predefined ITU frequency of the subchannel'"'"'s corresponding ITU channel;
(b) one or more lasers that can be tuned to generate modulated client signals at frequencies associated with each subchannel;
(c) a multiplexer that can combine the modulated client signals for transmission onto the fiber optic cables of the optical network; and
(d) either (i) a client signal multiplexer that can combine a plurality of client signals into a single higher-rate signal that can be mapped to a distinct subchannel, or (ii) a client signal inverse multiplexer that can divide a client signal having a data rate into a plurality of signals including a first signal that can be mapped to a subchannel of a first ITU channel, and a second signal that can be mapped to a subchannel of a second ITU channel different from the first ITU channel.
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Accused Products
Abstract
The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Tunable lasers are employed to generate respective subcarrier frequencies which represent subchannels of an ITU channel to which client signals can be mapped. In one embodiment, subchannels are polarization interleaved to reduce crosstalk. In another embodiment, polarization multiplexing is used to increase the spectral density. Client circuits can be divided and combined with one another before being mapped, independent of one another, to individual subchannels within and across ITU channels. A crosspoint switch can be used to control the client to subchannel mapping, thereby enabling subchannel protection switching and hitless wavelength switching. Network architectures and subchannel transponders, muxponders and crossponders are disclosed, and techniques are employed (at the subchannel level/layer), to facilitate the desired optical routing, switching, concatenation and protection of the client circuits mapped to these subchannels across the nodes of a WDM network.
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Citations
60 Claims
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1. An optical subchannel muxponder that can transmit optical signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the optical subchannel muxponder comprising:
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(a) a subchannel mapper that can map each of a plurality of client signals to a corresponding subchannel within or across a plurality of ITU channels, wherein each ITU channel in the plurality of ITU channels has a predefined ITU frequency and a corresponding plurality of subchannels, and wherein each subchannel has an associated frequency with a predetermined offset from the predefined ITU frequency of the subchannel'"'"'s corresponding ITU channel; (b) one or more lasers that can be tuned to generate modulated client signals at frequencies associated with each subchannel; (c) a multiplexer that can combine the modulated client signals for transmission onto the fiber optic cables of the optical network; and (d) either (i) a client signal multiplexer that can combine a plurality of client signals into a single higher-rate signal that can be mapped to a distinct subchannel, or (ii) a client signal inverse multiplexer that can divide a client signal having a data rate into a plurality of signals including a first signal that can be mapped to a subchannel of a first ITU channel, and a second signal that can be mapped to a subchannel of a second ITU channel different from the first ITU channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A system for multiplexing, transmitting and demultiplexing polarization-multiplexed signals, the system comprising:
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(a) a polarization combiner that combines a first set of signals aligned along a first linear polarization axis with a second set of signals aligned along a second linear polarization axis, wherein the first and second polarization axes are orthogonally polarized; (b) a transmitting medium which can modify polarization states of the first and second sets of signals, but will maintain orthogonality of the polarization between the sets of signals; (c) a polarization tracker that receives a plurality of transmitted signals from the first and second sets of signals, and modifies the polarization states of the received signals to transform the polarization state of the first set of signals to a first output linear polarization axis, and correspondingly transform the polarization state of the second set of signals to a second output linear polarization axis that is orthogonal to the first output linear polarization axis; (d) a polarization beam splitter at the output of the polarization tracker with one of its output linear polarization axes aligned with the first output polarization axis of the polarization tracker, and the other output polarization axis aligned with the second output polarization axis of the polarization tracker; (e) feedback circuitry that monitors and analyzes one or both outputs of the polarization beam splitter, and provides a control signal back to the polarization tracker to align the signal polarizations of the first set of signals with the first polarization axis of the polarization beam splitter, and to align the signal polarizations of the second set of signals with the second polarization axis of the polarization beam splitter; (f) at least one optical filter at the output of each branch of the polarization beam splitter that demultiplexes the signals in each linear polarization; and (e) a client signal inverse multiplexer that divides a client signal having a data rate into a plurality of signals each having data rates lower than the date rate of the client signal, the plurality of signals including the first set of signals and the second set of signals, wherein a first signal from the first set of signals is mapped to a subchannel of a first ITU channel, and a second signal from the second set of signals is mapped to a subchannel of a second ITU channel different from the first ITU channel. - View Dependent Claims (14, 15, 16)
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17. A method for transmitting optical signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the method comprising the following steps:
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(a) mapping each of a plurality of client signals to a corresponding subchannel within or across a plurality of ITU channels, wherein each ITU channel in the plurality of ITU channels has a predefined ITU frequency and a corresponding plurality of subchannels, and wherein each subchannel has an associated frequency with a predetermined offset from the predefined ITU frequency of the subchannel'"'"'s corresponding ITU channel; (b) tuning one or more lasers to generate modulated client signals at frequencies associated with each subchannel; and (c) combining the modulated client signals for transmission onto the fiber optic cables of the optical network; and (d) either (i) combining a plurality of client signals into a single higher-rate signal that can be mapped to a distinct subchannel, or (ii) dividing a client signal having a data rate into a plurality of signals each having data rates lower than the data rate of the client signal, the plurality of signals including a first signal that can be mapped to a subchannel of a first ITU channel, and a second signal that can be mapped to a subchannel of a second ITU channel different from the first ITU channel. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method for multiplexing, transmitting and demultiplexing polarization-multiplexed signals, the method comprising the following steps:
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(a) combining a first set of signals aligned along a first liner polarization axis with a second set of signals aligned along a second linear polarization axis, wherein the first and second polarization axes are orthogonally polarized; (b) launching the combined signals onto a transmitting medium which can modify polarization states of the first and second set of signals, but will maintain orthogonality of the polarization between the sets of signals; (c) receiving a plurality of transmitted signals from the first and second sets of signals, and modifying the polarization states of the received signals to transform the polarization state of the first set of signals to a first output linear polarization axis, and correspondingly transform the polarization state of the second set of signals to a second output linear polarization axis that is orthogonal to the first output linear polarization axis; (d) splitting the first set of signals aligned with the first output polarization axis from the second set of signals aligned with the second output polarization axis; (e) monitoring and analyzing one or both of the split sets of signals, and generating a control signal to align the signal polarizations of the first set of signals with the first output linear polarization axis, and to align the signal polarizations of the second set of signals with the second polarization axis; and (f) demultiplexing the signals in each linear polarization; (g) dividing a client signal having a data rate into a plurality of signals each having data rates lower than the data rates of the client signal, the plurality of signals including the first set of signals and the second set of signals; and (h) mapping a first signal from the first set of signals to a subchannel of a first ITU channel, and a second signal from the second set of signals to a subchannel of second ITU channel different from the first ITU channel. - View Dependent Claims (30, 31, 32)
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33. An optical subchannel muxponder that can transmit optical signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the optical subchannel muxponder comprising:
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(a) a first plurality of lasers, each of which is tuned to generate a subfrequency at a predetermined offset from a first predefined ITU frequency, wherein the first predefined ITU frequency constitutes a first ITU channel and the subfrequencies constitute subchannels of the first ITU channel; (b) a second plurality of lasers, each of which is tuned to generate a subfrequency at a predetermined offset from a second predefined ITU frequency, wherein the second predefined ITU frequency constitutes a second ITU channel different from the first ITU channel and the subfrequencies constitute subchannels of the second ITU channel; (c) an inverse multiplexer that divides a client signal having a data rate into a plurality of signals each having data rates lower than the data rate of the client signal, the plurality of signals including a first signal that is mapped to a subchannel of the first ITU channel, and a second signal that is mapped to a subchannel of the second ITU channel; (d) a first modulator that modulates the first signal onto the subfrequency of the subchannel to which it is mapped, generating a first modulated subchannel signal of the first ITU channel; (e) a second modulator that modulates the second signal onto the subfrequency of the subchannel to which it is mapped, generating a second modulated subchannel signal of the second ITU channel; and (f) a multiplexer that combines the first and second modulated subchannel signals into an optical signal for transmission onto a fiber optic cable of the optical network. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46)
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47. A method for transmitting optical signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the method comprising the following steps:
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(a) tuning each of a first plurality of lasers to generate a subfrequency at a predetermined offset from a first predefined ITU frequency, wherein the first predefined ITU frequency constitutes a first ITU channel and the subfrequencies constitute subchannels of the first ITU channel; (b) tuning each of a second plurality of lasers to generate a subfrequency at a predetermined offset from a second predefined ITU frequency, wherein the second predefined ITU frequency constitutes a second ITU channel different from the first ITU channel and the subfrequencies constitute subchannels of the second ITU channel; (c) dividing a client signal having a data rate into a plurality of signals each having data rates lower than the data rate of the client signal, the plurality of signals including a first signal that is mapped to a subchannel of the first ITU channel, and a second signal that is mapped to a subchannel of the second ITU channel; (d) modulating the first signal onto the subfrequency of the subchannel to which it is mapped, generating a first modulated subchannel signal of the first ITU channel; (e) modulating the second signal onto the subfrequency of the subchannel to which it is mapped, generating a second modulated subchannel signal of the second ITU channel; and (f) combining the first and second modulated subchannel signals into an optical signal for transmission onto a fiber optic cable of the optical network. - View Dependent Claims (48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60)
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Specification